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排序方式: 共有109条查询结果,搜索用时 31 毫秒
81.
西北作为资源开发主导型地区 ,矿产资源和水资源在开发利用过程中 ,存在一系列问题。兵团在新疆具有举足轻重的地位 ,应该协调该地区资源开发与环境保护 ,在可持续发展道路中采取相应的对策。  相似文献   
82.
生长调节剂对微生物生长及甾体微生物转化的影响   总被引:1,自引:0,他引:1  
利用正交实验考察了生长调节剂NGS、NNX和ONX对菌体生长及甾体微生物转化的影响.找出了生长调节剂的有效主组分(NGS)、辅助组分(NNX、ONX)及最佳配比新型生长调节剂NGS-NNX(NGS: 0.76×10 -6g/mL,NNX:1.28×10 -6g/mL).最佳配比新型生长调节剂的加入,促进了菌体生长和酶催化反应,表现为菌体量增多,发酵液最低pH值降低,甾体转化增强.同时,还对生长调节剂的生物效应进行了初步的探讨.  相似文献   
83.
《防务技术》2020,16(3):609-616
The high-speed impact of a projectile on a liquid-filled tank causes the hydraulic ram, in which a cavity is formed. To study the growth characteristics of the cavity, the formation mechanism of the cavity is analyzed. The effect of Reynolds number and Mach number on drag coefficient is considered, the axial and radial growth models of the cavity are established respectively. The relative errors between the cavity length calculated by the axial growth model, the cavity diameter calculated by the radial growth model and Ma L. Y. test results are less than 20%, which verifies the effectiveness of the axial and radial growth models. Finally, numerical simulation is carried out to study the growth characteristics of the cavity caused by the projectile impacting the satellite tank at the velocity of 4000 m/s. The cavity length and diameter calculated by the axial and radial growth models agree well with those obtained by simulation results, indicating that the cavity length and diameter in satellite tank can be accurately calculated by the axial and radial growth models.  相似文献   
84.
Operating costs per unit of input or output are often claimed to grow faster in defence than elsewhere in the economy. In this paper, we outline several possible reasons as to why operating costs increase at higher rates in defence, including differences in the input factor mix and productivity growth, the technological complexity required to maintain the relative effect of weapon systems and a gradual reduction in the number of units and activity. We investigate whether operating costs grow at a faster rate than elsewhere in the economy, by estimating growth in real output unit costs in the Norwegian Armed Forces for the period 1994–2013, using activity as a measure of output. We find no increase beyond general inflation in structural (fixed) costs, whereas activity-based (variable) costs per unit of activity increase significantly.  相似文献   
85.
分析了在给定圆域D及D内的障碍点集V后,用于生成基本避障圆的几个性质定理.然后由这些定理提出了求最大避障圆的一种新算法.用这种方法可降低计算的复杂性和便于人工作图.  相似文献   
86.
Possession of a brand is a sine qua non for economic success, not least because it connotes trust in delivering the value promised. Although Western arms exporters offer branded systems whose sales are influenced by price, there is a plethora of other economic variables, such as offset requirements and life-cycle support. Entrants to the international arms market will struggle without such arms “packages.” China’s entry, however, goes beyond the traditional economic paradigm. A four-stage historical model offers the backdrop for identifying the drivers that have forged its market entry into 55 countries worldwide. The strategy initially focused on sales of rudimentary military equipment for political purposes, but recently it has begun to commercialize exports, repositioning them from a low- to a high-tech sales trajectory. A Sino “brand” is thus emerging, reflecting both competitiveness and diplomatic considerations, especially non-interference in client state domestic affairs.  相似文献   
87.
良好的测试性设计对系统维修性具有重要意义,测试性增长试验通过一系列测试性设计缺陷发现和纠正措施,可保证系统测试性指标达到设计要求。针对基于延缓纠正的测试性增长过程中的资源配置问题进行研究,基于增长试验目标是否明确和试验资源是否受限制问题构建资源优化配置模型,并提出一种基于拉格朗日松弛和本地搜索的快速优化算法。仿真结果表明:该模型能够有效指导测试性增长中的资源优化配置问题,所提混合优化方法能够高效、准确地求解整数规划问题。  相似文献   
88.
Using annual data collected from 1988 to 2015, this study provides evidence of a non-linear relationship between military spending, economic growth and other growth determinants for the South African economy. The empirical study is based on estimates of a logistic smooth transition regression (LSTR) model and our empirical results point to an inverted U-shaped relationship between military spending and economic growth for the data. Furthermore, our empirical results suggest that the current levels of military spending, as a component of total government expenditure, are too high in the South African economy and need to be transferred towards more productive non-military expenditure in order to improve the performance of economic growth and other growth determinants.  相似文献   
89.
The relationship between economic growth and military expenditure has been the subject of a large literature in defence economics. This study analyses the influence of military expenditures on economic growth in a global perspective for the time period 2000–2010 taking spatial dimension into account. The augmented Solow model is employed to investigate the defence-growth nexus using the cross-sectional data relating to 128 countries. Following a traditional regression analysis, spatial variations in the relationships are examined utilizing different spatial econometric specifications estimated by maximum likelihood. The regressions are compared with each other via likelihood ratio tests, and the spatial Durbin model is found to be the most appropriate one suggesting that the typical least-squares model is misspecified. Empirical evidence indicates that military expenditure has a positive effect on economic growth with a significant spatial dependence for the time period under consideration.  相似文献   
90.
The paper analyzes the effects of military spending on economic growth in a small open stochastic endogenous growth model involving the supply-side and demand-side effects produced by military spending. We show that a rise in the military spending affects economic growth through four channels, including the crowding-out effect, the spin-off effect, the resource mobilization effect, and the portfolio effect. The net effect which depends on these four channels is ambiguous. Hence, we demonstrate that there exists an optimal defense burden that maximizes the economic growth rate.  相似文献   
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